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Bichler B.,Institute of Applied Synthetic Chemistry | Holzhacker C.,Institute of Applied Synthetic Chemistry | Glatz M.,Institute of Applied Synthetic Chemistry | Stoger B.,Institute of Chemical Technologies and Analytics | Kirchner K.,Institute of Applied Synthetic Chemistry
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials | Year: 2015

The systematic twinning of three 2,6-diaminopyridine-based Fe-PNP complexes is interpreted using order-disorder (OD) theory. The monoclinic [Fe0(PNPEt-iPr)(CO)2] [P1121/b, Z′ = 4] possesses pseudo-orthorhombic metrics and crystallizes as a reflection twin by pseudo-merohedry with the twin plane (100). The structure is made up of layers with idealized p21 a(b) symmetry. The a glide planes of adjacent layers do not overlap, leading to OD polytypism. trans-[FeII(PNP-Et)Br2(CO)] [P21/n, Z′ = 1] is systematically twinned via twofold rotation about [001]. It is made up of OD layers with idealized p2121(2) symmetry. OD polytypism is caused by the twofold rotation axes of adjacent layers which do not overlap. [FeII(κ2 P,N-PNP-iPr,TAD)Cl2]·THF [P1, ] is systematically twinned via a twofold rotation about [010]. It is made up of layers with idealized p121(1) symmetry. OD polytypism is caused by screw rotations relating adjacent layers with an intrinsic translation along a fourth of a primitive lattice vector. In all three structures the twin individuals are a polytype with a maximum degree of order (MDO) and at the twin interface is located a fragment of the second MDO polytype. © 2015 International Union of Crystallography.


Kubel F.,Institute of Chemical Technologies and Analytics | Pantazi M.,Institute of Chemical Technologies and Analytics | Hagemann H.,University of Geneva
Zeitschrift fur Anorganische und Allgemeine Chemie | Year: 2014

The compound Ba5I2O12 was synthesized by heating a precipitate of dissolved Ba(OH)28H2O and H5IO6. Rb2 O was added to increase the crystallite size. The crystal structure was determined from conventional laboratory X-ray diffraction data by using a real-space structure solution approach followed by a Rietveld refinement. No constraints on positions were used. The structure analysis gave an ortho-rhombic symmetry with a = 19.7474(2) Å, b = 5.9006(1) Å and c = 10.5773(1) Å. The final RBragg value in space group Pnma (62) was 1.0%. The structure can be described by layers of a metal and iodine arrangement forming almost pentagonal holes. Raman measurements were correlated with the two IO6 octahedra. Two further barium periodate patterns were observed and indexed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kubel F.,Institute of Chemical Technologies and Analytics | Pantazi M.,Institute of Chemical Technologies and Analytics | Wandl N.,Institute of Chemical Technologies and Analytics | Hagemann H.,University of Geneva
Zeitschrift fur Anorganische und Allgemeine Chemie | Year: 2014

In analogy to the synthesis of polycrystalline M2NaIO6 (M = Ca, Sr, Ba) by precipitation in water at 90 ° C, the title compound was first prepared as a metastable compound. The stable modification of Pb2NaIO6 was obtained by a heat treatment to 400 ° C followed by cooling to room temperature. The crystal structure was refined from powder diffraction data [space group P21/c (14), a = 5.9040(2), b = 5.7526(2), c = 10.1104(3) Å, β = 125.341(1)° ]. On heating, at ca. 125 ° C, a phase transition to a cubic high temperature modification was observed. The crystal structure was refined from XRD data mea- sured at 200 ° C [space group Fm 3 m (225), a = 8.2678(1) Å]. Depending on the precipitation temperature between 90 ° C and 0 ° C, several metastable modifications were obtained, which can be distinguished by significantly different lattice parameters. The XRD pattern of a powder precipitated at room temperature is pseudocubic. The crystal structure was refined at room temperature in P21/c with a = 5.8201(4), b = 5.8473(4), c = 10.0798(5) Å, β = 125.074(3)° . This modification behaves almost as a cubic lattice on heating as found from XRD and DSC measurements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Brunauer G.C.,Institute for Energy Systems and Thermodynamics | Brunauer G.C.,NOVAPECC GmbH | Rotter B.,Institute for Energy Systems and Thermodynamics | Walch G.,Institute of Chemical Technologies and Analytics | And 5 more authors.
Advanced Functional Materials | Year: 2016

A solid-state photoelectrochemical cell is operated between 400 and 500°C under 365 nm UV light. The cell consists of a photovoltaic part, based on a La0.8Sr0.2CrO3/SrTiO3 junction, and an electrochemical part including a zirconia solid electrolyte with a shared (La,Sr)FeO3 electrode. The photovoltaic cell part leads to open circuit voltages up to 920 mV at 400°C. Upon UV light, this driving force is used in the electrochemical part of the cell to pump oxygen from low to high partial pressures, i.e., to convert radiation energy to chemical energy. This demonstrates the feasibility of high-temperature photoelectrochemical cells for solar energy storage. The detailed characterization of the different resistance contributions in the system by DC and AC methods reveals the parts of the cell to be optimized for finally achieving high-temperature photoelectrochemical water splitting. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Mitrovic N.S.,University of Kragujevac | Zlatkov B.S.,Volkswagen AG | Nikolic M.V.,University of Belgrade | Maricic A.M.,University of Kragujevac | And 3 more authors.
Science of Sintering | Year: 2012

In this study, properties of soft-magnetic manganese zinc ferrite manufactured by powder injection moulding - PIM technology were presented. A powder consisting of Mn1- xZnxFe2O4 with small addition of hematite α-Fe2O3 was mixed with an organic binder (wax and thermoplastic) to form ferrite feedstock. The ferrite feedstock was injected in a mould with a cavity shaped like a small cylinder with a hole on the main axis. Injection moulded samples were then solvent, thermally debinded and sintered in air atmosphere. Structure of sintered sample was characterized using X-ray diffractometry, scanning electron microscopy and thermomagnetic measurements. Magnetic properties were measured by hysteresis graph at different frequencies up to 1 kHz. Sintered sample contains a mixture of two phases Mn0.6Zn0.4Fe2O4 (68 wt. %) and α- Fe2O3 (32 wt. %). The Curie temperature is TC ≈ 220 °C for the green sample but after the heating up to 470 °C, TC increase up to about 300 °C. The high increase of normalized magnetic permeability of about 800 % was observed due to melting and burning of binder. The hysteresis loop of sintered MnZn ferrite toroidal cores has an R-shape with saturation of 0.44 T and remanence ratio of 0.49. The low value of coercivity (only 47 A/m) was related to the presence of α-Fe2O3 crystalline phase and attained already optimum density (ρ ≈ 4.8 g/cm3) i.e. observed low level of porosity. Attained relative magnetic permeability μr ≈ 2000 as well as power losses Ps ≈ 21 W/kg for sintered sample (at 1 kHz; 0.39 T) is in agreement with the MnZn ferrite commercial samples.

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